Carving fixture



' Dec. 7, 1943. P. w. BROWN cARv'INe FIXTURE Filed Jan. 51, 1941 6 Sheets-Sheet 1 I IQVENTQR PERI? Y w. BRO w/v.

-r'r DR NEY I Dec. 7, P. W. '2335,995

- cmvme FIXTURE Filed Jan. 1,1941 6 Sheets-Sheet 2 I f 12' I v I INVENTQRA BRWN.

P. W. BROWN CARVING FIXTURE Filed Jan. 31,

IH U INVENTOR PERRY w. mow BY ATTORNEY M I H a D Dec. 7; 1943.

Dec. 7, .1943. P. w. BROWN CARVING FIXTURE Filed'Jan. 31,1941

6 Sheets-Sheet 4 INVENTOR 4 PERRY Manon/M "WrTbRNEY- Dec. 7, 1943. P. w. BROWN 2,335,995

CARVING FIXTURE Filed Jan. 31, 1941 6 Sheets-Sheet 5 INVENTOR PERRY W. BROWN ATTORN EY Dec. 7, 1943. p w, BROWN I 2,335,995

I CARVING FIXTURE Fild Jan. 51, 1941 6 Sheets-Sheet 6 7 INVENTOR PERRY W. BROWN.

BY I

I \Q' a g ATTORNEY Patented Dec. 7, 1943 2,335,995 7 CARVING FIXTURE Perry W. Brown, Ridgewood, N. J., assignor to Wright Aeronautical Corporation, a corporation of New York Application January 31, 1941, Serial No. 376,778

1 Claim.

This invention relates to machine tools and more particularly to feed fixtures for milling or carving machines.

An object of the invention is to provide a movable work holding fixture cooperating with a rotating cutter by which axially waved annular surfaces or grooves may be formed.

A further object is to provide tool equipment for cutting deep grooves whose depth varies according to a prearranged profile throughout the length of the groove.

A further object is to provide tool equipment for formed grooves curved in plan form and of changing depth wherein the side surfaces of the groove are sloped with respect to a datum axis.

Further objects of the invention will become apparent in reading the annexed detailed description in connection with the drawings, in

which:

Fig. 1 is a side elevation of a vertical milling machine equipped with a fixture of the invention;

Fig. 2 is afragmentary side elevation showing the drive mechanism for the fixture;

Fig. 3 is a fragmentary front elevation of the milling machine and fixture;

' Fig. 4 is a section across the work table of the fixture comprising a section on the line 4-4 of Fig. 6;

Fig. 5 is a section on the line 55 of Fig. 4;

Fig. 6 'is a plan of the work table; and

Fig. 7 is a section on the line 7-! of Fig. 3.

Although the provisions of the invention are shown as applied to a vertical milling machine, the teachings may be used in connection with other types of machine tools. In particular, the mechanism of the invention is adapted for the formation of valve ports in the cylinder heads of internal combustion engine cylinders for aircraft. Such cylinder heads have in the past been formed from castings whereas it is now contemplated to form them from forgings of non-ferrous materials such as copper or aluminum alloys, by which better mechanical properties of the forgings may be utilized in high performance engines, since the cylinder head castings previously used have limitations in their mechanical properties diminishing their utility as the power output of aeronautical engines is increased. Many of the machining operations. for cylinder head forgings may be accomplished by relatively simple. turning, boring, or milling operations but the profiling of the valve. ports is a machining operation of complicated character which is not readily accomplished by conventional machining operations. Thus, the fixture of this invention was developed by which the profiling of the valve ports may be accomplished in a single feeding operation, the Valve ports comprising in general a deep annular groove whose depth varies throughout its'circumference. A further peculiarity of the valve port profile is that the sides of the groove forming the port comprise conical elements which are not parallel either with the valve axis or with any other axis or plane of the cylinder head structure.

As will shortly be apparent, the provisions of this invention enable this odd-shaped valve port to be formed with great facility and although particularly adapted for forming valve ports, the fixture of the invention may be readily adapted for forming or carving odd-shaped elements in machine parts other than engine cylinder heads.

Referring now to the drawings, Figs. 1, 2 and 3 show a more or less standard vertical milling machine comprising a base ID, a standard II, and a head [2 from which depends a vertical cutter spindle 53 carrying a cutter I4 which for the purpose of profiling valve ports is an end mill with a hemispherical end. The spindle I3 is adapted to be rotatably driven by earing and other apparatus, not shown, forming a normal part of a vertical milling machine.

The standard H is provided with vertical way l5 supporting a knee IS, the knee being shiftable vertically upon the ways l5 by a suitable power feed, not shown, or by a screw jack i'l between the base l0 and the knee l6.

As will be apparent from Figs. 2, 3, and '7, the knee l6 comprises a bed carrying drive gearing and ways l8 in which a support [9 is mounted for vertical reciprocation. Upon the top of the support. i9 is mounted an element 20, reciprocable with the support l9, upon which a work table 2| is mounted for rotation on an axis which is tilted with respect to the axis of the spindle I3.

A feed power shaft i l is journalled in the knee IS on a side thereof and is driven by a suitable power source, not shown, this power shaft carrying a bevel gear 26 meshed with a bevel gear 2'l on a vertical axis whose shaft 28 is journalled in the knee and in a gear box 29 carried by the member 28, the journals of the gear box 29, along with a bevel gear 30 mounted on the shaft 28, being vertically slidable along the shaft 28vas themember 29 reciprocates in a vertical direction. p g j;

The power shaft 24 also carries a worm 32 driving a worm Wheel 33 secured to a shaft 34 journalled in and extending across the lower end of the knee It, the opposite end ofthe shaft 34 mounting a pinion 36 meshed with a gear 31 mounted on a shaft 38 journalled in the knee as at 39 and 40. Centrally of the shaft 38 is a cam 42 upon which rests a roller 43 idling on a shaft 44 journalled in the support 19. It is apparent that there is a substantial speed reduction from the power shaft 24 to the cam 42 so that, as the power shaft 24 rotates, the support l9 will slowly move up and down, following the profile of the cam 42 which cam may readily be replaced as different degrees of support rise are desired or as changes are required in the type of vertical reciprocative motion of the support I9.

The member 20, on which the work table 2! is journalled on its tilted axis, as shown in Figs.

4, and 6, is provided with bearings 41 carrying a shaft 48 to which a bevel gear 49 is secured for engagement with the bevel gear 39, said shaft 48 carrying a worm 5i engaged with a worm wheel 52 secured to a plate 53 which forms a mounting for the work table 2!. Between the plate 53 and the member 29 is a thrust bearing 55 and a plurality of bearings 5% by which a spindle 51 for the table 21 is accurately held, said spindle being secured to the table 2!. Oil seals 53 and 58' are provided in the table mounting system to retain lubricating oil in the member 20 for lubricating the several bearings and the worm and wheel drive. To the member 28, a pan or shield 59 is secured to catch that cutting oil or cutting compound fed to the work being operated upon, such and is held by a clamp '51, the valve guide opening of the rocker box being located concentric with the axis of the table 21 by a locating plug 69 passed therethr-ough and into a bushing engaged with the pad 68. A bracket 12 is secured to the table 2| and is provided with a pad 13 upon which the top face of the rocker box 65 rests, the pad '13 being provided with a clamping device engaging a portion of the rocker boX to secure it against displacement.

For the particular job of profiling valve ports, drive gearing for rotation of the work table 2| and for reciprocation of the support i9 will be so organized that the table 2! makes one complete revolution while the cam 42 makes one complete revolution. Thus, when the cylinder head blank 62 is set up on the table 2|, and When the knee I6 is raised so that the cutter l4 engages the workpiece, the feed drive shaft 24 will be started so that as the work piece turns, it is gradually raised and lowered with respect to the cutter 5:1, thereby forming the valve port groove 83 as a substantially annular groove whose depth varies throughout its periphery. Obviously, the depth variation is obtained from an appropriate profile on the cam 42. The diameter'of the groove 33 is established by the lateral position of the member 29 with respect to the axis of the cutter Hi. The slope of the sides of the groove 83 with respect to the axis of the valve guide and thus with respect to the axis of the table 2| is established by the tilt of the aXis of the table 21 with respect to the axis of the cutter I4. For any predetermined job on a cylinder head, the slope of the groove 63 will be established and the member 2%] may be constructed accordingly, the bevel gears 33 and 49 for rotatably driving the table being chosen in accordance with such tilt. If a different degree of tilt is desired, the position of the member 2%] and the relative angles of the gears 30 and 49 will be chosen accordingly.

It is apparent that the cam 42 may be varied in form and varied as to the number of lobes thereon to secure different forms of cut by the cutter [4. For instance, a two lobe cam would cause the valve port groove 63 to have two high points and two low points, instead of one high point and one low point as obtained through the use of the single lobe cam 42. The desired profile for the bottom of the groove 63 is secured merely by replacing the cam 42 by one appropriate to the new profile.

In the above description, the various mountings and bearings for the component parts have not been described in detail since it is considered that the appropriate choice of bearings and mountings will be apparent to one skilled in the art. The sliding connection between the gear 30, which is journalled in the gear box 29, and its drive shaft 28 may comprise a keyed arrangement or a splined arrangement as desired. In fact, some of the gearing shown in the drawings could be replaced by other forms of power transmission, so long as the feed relationship of the rotating table and the means for reciprocating the rotating table is maintained to secure the desired motion of the work piece mounted upon the work table.

It is also considered to be within the scope of the invention to use other sorts of carving cutters I4 than that depicted. In some classes of work, the provisions of the invention might be used in connection with horizontal rather than vertical milling machines or in machine tools where the cutter might be stationary rather than rotative.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without de-' parting from the spirit or scope thereof. I aim in the appended claim to cover all such modifications and changes.

I claim as my invention:

In a milling machine for cutting an annular groove in a work piece, a rotatable end mill cutter, a rotatable work table adapted to carry a work piece into engagement with said cutter, means for rotating said table about an axis which is inclined to the axis of said cutter and disposed parallel to the axis oi the annular groove to be cut, said cutter axis being so disposed that it is at all times parallel to that portion of the side Walls 01" said groove in contact with said cutter, and means operative simultaneously and in timed relation to the rotation of said table for effecting relative reciprocation of said table and cutter along a path parallel to the axis of said cutter so that said machine is adapted to cut an annular groove of varying depth in said work piece with the side walls of said annular groove inclined to the axis of said groove.

PERRY W. BROWN. 

